A descender is a device that is conventionally attached to a seat or girding belt, through which has been threaded a single rope or line, which enables a person to effect a controlled descent. Control is exercised during the descent by alternately tightening and loosening the untethered end of the rope on which the person is descending. Such tightening and loosening has the effect of snubbing and releasing the rope as it travels through the particular threading pattern in the descender. Conventionally, descenders are comprised of one or more pieces of rigid, durable and abrasion-resistant material.
The traditional, and often used, descender is a singular device in the shape of an inverted "figure-eight". The smaller, (lower) loop of the "figure-eight" is attached to the girding belt or seat (harness) of the user by a snap link, commonly referred to as a carabiner. The rope to be descended is generally set out, unextended and untethered. The end to be tethered is passed first into the top or larger ring of the "figure-eight", out and back around the connecting bridge (between the two loops) and through the larger ring or loop, in the direction opposite its insertion. The rope is then tethered and the remainder is cast over the precipice which is to be descended.
After the threading of the descender, the user must tighten the portion of the rope which is tethered and firmly grasp the untethered portion over which he will descend. Once the descent is begun, the threading of the rope through the descender in conjunction with the particular geometry of the descender, allows the formation of a stylized "slip-knot" which may be alternately tightened and loosened by the user. The tightening is effectively a snubbing, caused by pulling downward on the untethered portion of the rope; while, loosening of the stylized knot is effected by carefully releasing the downward tension on the untethered portion of the rope. This alternate tightening and loosening of the stylized knot on the descender, allows a controlled descent on the rope.
Generally, in the hands of an experienced user, the traditional "figure-eight" descender may be used effectively and with relative safety. However, the most experienced user encounters two very prominent problems with the use of the "figure-eight" descender. The first is often manifested if the untethered portion of the rope is slackened excessively. This occurs when the user is attempting to descend very rapidly. Essentially, the stylized knot on the descender loosens and slips up and over the upper or larger loop of the inverted "figure-eight". This has the effect of knotting the rope away from the point of snubbing (and control). As a result, the user must physically pull himself upward and loosen the knot, bringing it back to its proper snubbing configuration, with the rope passing essentially through and around the junction of both loops in the "figure-eight". For the uninitiated, this can be an arduous, if not dangerous, maneuver because the user could very easily exhaust himself.
Relative to the aforementioned problem, some "figure-eight" descenders have been modified to preclude the rope passing completely over the larger loop or ring of the "figure-eight". This has been accomplished by the addition of two tab-like members placed opposite to each other, at the top of, and tangential to the larger ring. These tabs are known as "ears" and, in fact, give an appearance of an inverted "figure-eight" with ears. They have the function of preventing the stylized knot from completely slipping off the larger ring of the "figure-eight" descender. Although this safety adjunct does effectively prevent a complete halt to the descent, it nonetheless does not avoid an occurrence of the problem; it simply avoids the most hazardous aspects of the problem. The instant invention avoids the aforementioned problem completely by utilizing a different form of threading, a form that is obtainable only through use of the invention's unique geometry.
The second most commonly encountered problem using traditional descenders is one which is inherent in the design of all descenders that require a prethreading before use. The traditional "figure-eight" descender must, as pointed out above, be threaded before the rope is either extended or tethered. Usually, the descender is threaded and then attached to the belt or seat carabiner. As will be pointed out more clearly in the Detailed Description of the Preferred Embodiment, the threading of the traditional "figure-eight" descender does not allow a rapid threading while the descender is still connected to the user. The instant invention achieves significant utility in that it may be threaded while attached to the user and, in the case of a seasoned experienced user, may be threaded and even replaced during the descent.
Briefly, the present invention avoids the most significant problems of the conventional art by providing a unitary rappelling tool that is comprised of a rigid, durable, abrasion-resistant material such as aluminum. It consists of a planar ring structure having at least two coplanar essentially orthogonll projections, one of which contains an aperture for linking the device to a users seat or belt apparatus. The second projection, hereinafter referred to as a second tab, serves as a capstan around which the cord or rope may be wound or threaded. In the preferred embodiment, this tab has protrusions or extensions therefrom. Such protrusions or extensions on the capstan-like tab serve only to assure that the rope will not slip off the tab, under any condition.
The orthogonal placement of the tabs in relation to the planar ring lends both the utilitarian and novel character to the invention. In conjunction with the various threading configurations hereinafter discussed, the invention provides reasonable, safe solutions to the two most prominent problems that have plagued climbers since the inception of the sport and the first use of the "figure-eight" descender.